To those whom have flown the route LAX-JFK I will bet non of you flew the great circle route to get there.
I have seen QF planes fuelled LAX-JFK with 90 - 100 K of fuel during the Tornado season, with accompanying flight plans flying over gulf of Mexico to Florida before making a left to fly up the coast via walla walla washington to JFk, or flying adjacent the Canadian border as far as SEA-TAC then down the coast for LAX.
Even with a 777-200ER you may not be able to make the distance SYD - JFK